Final answer:
The kinetic molecular theory explains gas behavior, showing that at a given temperature, heavier molecules like xenon move slower than lighter molecules like argon, which can be depicted with varying tail lengths in visual models.
Step-by-step explanation:
Understanding Gases through Kinetic Molecular Theory
The kinetic molecular theory of gases provides an explanation for the properties of gases by modeling them as small, hard spheres with insignificant volume, in constant motion, and undergoing perfectly elastic collisions. According to this theory, the average kinetic energy (KEavg) of gas molecules is the same for all gases at a given temperature, regardless of the molecular mass. However, because the kinetic energy depends only on temperature, lighter molecules will have higher speeds compared to heavier molecules at the same temperature.
Given a gas sample containing equal molar amounts of xenon and argon, depicted by kinetic molecular theory, we would see red dots (xenon) and blue dots (argon) with tails representing their velocities. As the diagrams from the theory suggest, we would expect that, at the same temperature, xenon atoms (being heavier) would have shorter tails (indicating lower speeds) than argon atoms (which are lighter and thus would have longer tails for higher speeds).
This behavior of the molecules can be seen in the average root mean square speed (Urms) trend, where heavier noble gases like xenon show a distribution of speeds peaking at lower values, whereas lighter ones like argon peak at higher speeds. This concept is crucial in the depiction of gas samples in kinetic molecular theory and can be visualized through illustrations that incorporate this difference in molecular speed based on the mass of the gas particles.